1. Field of the Invention
The present invention relates to optical scanners that convert graphic information and printed text to digital signals. More particularly, the present invention relates to hand-held optical scanners.
2. Discussion of Related Art
Hand-held scanning wands are well known in the art. These wands are stroked across graphical information such as a strip of bar code or a line of text and, in cooperation with electronic devices located in the wand or communicating with the wand, convert the graphical information into digital signals that can be processed by a computer.
For scanning bar code, the wand need only pass from one end of a bar code strip to the other, without regard to the wand's vertical placement within the strip. However, when other graphical images are scanned, particularly printed text, the position of the wand on the line of text along the axis normal to the wand's line of travel down the line of text affects the usefulness of the converted information. In particular, where the wand is used in conjunction with optical character recognition (OCR) software to convert printed text to computer-usable text, e.g. ASCII code, entire characters must be scanned in the course of each such stroke of the wand in order to assure that the characters will be accurately reproduced when the line of text is converted to digital data by the OCR software.
Thus, it is critically important that the top and bottom edges of the line of text remain within the detection zone of the wand as it is stroked along a line of text. However, the smaller and more convenient a wand is to use, the smaller the detection zone at the tip of the wand will be, and a smaller detection zone makes it more difficult to maintain the necessary alignment between the tip of the wand and the line of text.